Multi Chip Module (MCM) devices typically have a number of semiconductor chips or other components attached to a substrate having electrical interconnects connecting the components to each other to provide a compact, versatile module. After assembly of an MCM, it is often necessary to test the function of the device. Traditionally, a probe card having needle-like probes each contacting a conductive land was employed to provide a connection to external test circuitry. However, in high speed devices operating in the 100 Mhz-1 GHz range, the long probes suffer parasitic resistance, capacitance, and inductance that prevents proper testing. For this reason, test chips have been directly connected to devices under test, by making direct contact between raised conductive bumps on the chip and conductive lands on the substrate.
MCM devices can be produced in a multitude of sizes and configurations to perform innumerable functions. Therefore, a single test chip would likely have inadequate capacity for some complex applications, and excess capacity and needless cost for other simpler applications. As an alternative, custom test chips may be created, but this increases costs associated with design and fabrication, as well increasing the time until a chip is available for use.
Accordingly, there is a need for a low cost test chip configuration that provides a wide range of possible capabilities with a standard design. This is provided for a multi chip module with a substrate having a network of a plurality of electrical interconnects and a number of electronic components mounted to the substrate and connected to the network. A monolithic test chip having a number of identical functional regions is mounted to the substrate and electrically connected to the network. Each functional region on the test chip is independently connected to the substrate and is electrically isolated from the others. The chip may be produced by preparing wafers with a grid of identical functional elements, and cutting up the wafers into test chips of different sizes. Test chips may have a variable number of functionally identical elements on a single chip, depending on the application.